Substance P (SP) is an undecapeptide that has been shown to be decreased in post-mortem human putamen and rat hypothalami in an age-related fashion. It is also known that there are specific SP degrading enzymes predominantly localized in the post-microsomal supernatant fraction (S3) of brain homogenates that lend to the formation of SP-related peptide fragments that have shown biological activity including alterations in behavior. These enzymes can be studied using in vitro time-course metabolism procedures of synthetic SP without saturating or altering them. It is our aim to biochemically characterize and examine the metabolism (processing) of SP in post-mortem human putamen from subjects with specific age-related disease vs age and sex matched control subjects. The hypothesis that we with to test is that the age-related decrease in SP from post-mortem putamen is due, in part, to an alteration in SP-degrading enzyme activity or content and an imbalance exists in the quantity of specific SP-related fragments. It may be possible that SP is not the only active peptide involved in dementias. SP may actually be eliciting some of its biological effects via active fragments of the parent peptide. Alterations in the formation of these SP-related "active" fragments may be a cause or result of certain dementia-related aging diseases. To accomplish these goals, we will couple the disciplines of analytical chemistry and neuropharmacology. Using high performance liquid chromatography (HPLC0 to separate and quantitate the various SP fragments, we plan to utilize a method which we previously documented for Beta-endorphin (BetaE) metabolism in order to study the metabolism of SP. This will be accomplished by time-course incubating synthetic SP with subcellular fractions prepared from post-mortem human putamen and cortex. Application of this new approach will allow us to explore the biochemistry and neuropharmacology of SP in senile dementia of the Alzheimer type (SDAT), using post-mortem brain tissue. We can determine if errors in the metabolism of SP are present in SDAT brain tissue and how this affects the levels of SP and behaviorally active SP-related fragments. Once these errors are isolated, possible treatment regimens, including drugs which alter peptidases, can be considered in the future.